Prosthetics

Question 1

What is a prosthesis?

Answer 1

• Is a device or artifical substitute designed to replace as much as possible the function or appearance of a missing limb or body part

Question 2

What’s the aim of prosthetic rehabilitation ?

Answer 2

• Enable the patient to achieve maximum functional independence with the prosthesis taking into account the patients premorbid abilities, lifestyle expectations

Question 3

For a successful outcome what are the dependent factors?

Answer 3

Patient factors-

• premorbid levels activity
• ability to learn new skills
• pathology of contralateral limb
• static and dynamic level
• sufficient trunk control
• other comorbidities

Prothesis factors

• comfortable
• easy don (on) and doff (off)
• appropriate components
• lightweight, durable, realiable
• cosmetically pleasing

Teamwork

• • appropriate communication between surgeon and rehab team.
• Surgeon operate with prostheis on mind

Question 4

Who are upper amputations more common in?

Answer 4

• Young men- secondary to trauma

Question 5

Who are lower limb amputations common in?

Answer 5

• Older population
• secondary to medical disease - PVD, DM

Question 6

For trash ossseous amputations what criteria should be born in mind for the ideal stump?

Answer 6

• Scar should be well healed and mobile away form subcutaneous edges
• Skin should be sensate as possible
• Stump should be cyclindricial or conical shape at closure
• excessives tissue distal to bone secretion should be avoided
• Traumatised tissue shouldn’t be retained
• Myoplastic techniques- suturing muscle to periosteum should be attempted although myodesis maybe used in transfemoral
• Nerves sectioned cleanly under gentle tension and allowed to retract prevent neuroma formation
• Bone ends should be Bevelled or contoured
• Non absorbable sutures must be avoided

Question 7

What is the optimism level of a prosthesis ?

Answer 7

• This achieved to allow limb fitting,common error stump left too long.
• Transradial forearm - optimal junction proximal 2/3rds and distal third of forearm.
  
  • Shortest 3cm below insertion of biceps brachii. Longest 5cm above wrist joint to allow spacer for wrist rotatory prosthesis
• Transhumeral - optimum middle third if humerus,
  
  • shortest 4cm below ant axillary fold,
  • longest 10 cm above olecranon to alow spaces for elbow mechanism.
• Tansfemoral- optimium middle third of thigh
  
  • shortest 8cm below pubis,
  • longest 15cm above medial joint line
• Trans-tibial- optimium 8cm for 1m height
  
  • , shortest 7.5 below knee joint,
  • longest level at which a myodesis carried out.

Question 8

What are the advantages of a dis articulation amputation ?

Answer 8

• The amputation retains the WB surface
• The Bulbous shape assists suspension of the prosthesis

Question 9

What are the disadvantages of a disarticulation amputation?

Answer 9

• Amputation can compromise the choice and or fitting of prosthesis
• The prosthesis can appear bulky-
• exception- symes amputation for CONGENTIAL absence of fibula with associated leg shortening. The shortening of the leg allows the bulb of the stump to be masked within the shaping of the external calf prosthesis

Question 10

How are prosthesis classified ?

Answer 10

1. By level of amputation - e.g. transfemoral
2. By structure
   
   • ** exoskeletal**= where the strength of the prosthesis is in the rigid external structure and all parts are fitted to it
   • Endoskeletal- modular where individual components are linked by internal struts and the whole assembly is covered with soft external cosmesis
3. By Function- cosmetic vs functional

Question 11

What are the common elements of a prosthesis ?

Answer 11

1. Socket/ interface
   
   • connection between the residual limb and the prosthesis
2. Suspension mechanism- attaches the prosthesis to the residium ( belts, wedges, straps or suction )
   
   • standard suction
     
     • ​form fitting or semi rigid socket which residium is fitted
   • elastomeric suction
     
     • ​silicone/gel based sleeve that slips onto residium, which is then inserted into socket
3. Struts/tubes (pylon) -intervening structure that restore limb length and attach the socket to the terminal device
4. Articulating joints- replace missing joint function
5. Terminal device- most distal part of the prosthesis ( in the ll= foot)

Question 12

What does the socket do?

Answer 12

• Protects the residual stump
• transmits the forces necessary for standing and ambulation
• Made by computer assisted technology or moulding of residium
• May need to be adjusted as volume of residium changes

Question 13

What are the 2 types of suspension mechanism?

Answer 13

1. Standard suction
   
   • form fitting or semi rigid socket into which residium is fitted
2. Elastomeric suction
   
   • silicone or gel based sleeve that slips onto the residium which is then inserted into the socket.
   • Combined with a proximal external sleeve and distal valve-> airtight seal that stabilizes the prosthesis

Question 14

What is the terminal device in a lower limb prosthesis cf a upper limb prosthesis?

what are the different types?

Answer 14

• LL= foot
• UL= Hand, Hook, gripper
• either passive ( less function but greater cosmesis)
• active ( more function less cosmesis)
  
  • ​powered by cables attached to harness**= body powered device **
  • action potentials from muscle contraction in the residum-= myoelectric device
  • voluntary opening -if lie closed at rest
  • voluntary closing- if lie open at rest

Question 15

What are the 5 different types of grip ?

Answer 15

1. Precision - pad thumb to index finger- pinching
2. Tripod- pad of thumb to index and middle finger
3. Lateral- thumb to lateral aspect of index finger
4. Hook power- small joints of finger flexed and thumb extended
5. Spherical - tips of fingers and thumb are flexed to open doorknob

Question 16

What may be used prior to fitting of a prosthesis?

Answer 16

• Skin desensitisation programme
  
  • massage ( to reduce excessive scar formation)
  • odema control ( elastic compression)
  • gentle tapping ( on distal aspect of residum to mature the site)
• use of a early training device
  
  • penumatic post amputation mobility aid or an upper limb gaunlet with a rudimentary device

Question 17

What are the options regarding timing ot fitting?

Answer 17

• Immediate
• Prompt
  
  • around 7-10 days when there is evidence of stump healing
• Early
  
  • 3 weeks after stump has healed
• Late
  
  • around 3-4/12 when the stump is fully matureof if there has been a delayed wound healing

Question 18

What are the complications of prosthesis ?

Answer 18

1. Psychosocial
2. Physical

Question 19

What are the physical complications?

Answer 19

• Dermatological - blisters
• Phantom sensation
• Phantom pain
  
  • stinging/burning/cramping worse at night
  • anticonvulsants/antidepressants/nsaids
  • majority temporary
• Choke syndrome
  
  • venous outflow obstruction from a narrow prox part of socket in combo with space distally
• Increase energy consumption

Question 20

What is phantom sensation ?

Answer 20

• Sensation that the amputated limb is still present

Question 21

What is phantom pain?

Answer 21

• Sensation of pain originating in the amputation part of the limb
• • stinging, burning or cramping .
• Tx with anticonvulsants, antidepressants, nsaids
• Mainly temporary

Question 22

What is choke syndrome ?

Answer 22

• Venous outflow obstruction of the residum occurring as a result of narrow in the proximal part of the socket in combination with an empty space more distally in the socket.

Question 23

What is the energy consumption for transtibial amputation?

Answer 23

• 25%

Question 24

What is the energy consumption for bilateral transtibial amputations?

Answer 24

• 20-40%

Question 25

What is the energy consumption for short transtibial amputation ?

Answer 25

* **40%**

Question 26

What is the energy consumption for transfemoral amputation ?

Answer 26

* **65%**

Question 27

What is the energy consumption for hip disarticulation?

Answer 27

* **\>100%**

Question 28

What is the energy consumption for bilateral transfemoral amputation ?

Answer 28

200%

Question 29

what is this?

Answer 29

* **_trans tibial prosthesis_** * **socket** * patella tendon bearing prosthesis * now total contact and total surface bearing ( where less patella tendon bearing adn weight distributed more evenly * **Suspension** * several options * supracondylar cuff * supracondylar extension to socket - patella tendon supracondylar * sleeve suspension- neoprene * elastic socket suspension * elastomere sleeve ( silcone or gel) suspension with locking pin or lanyard * Icelandic roll on sllicone socket * valve pump suction w elastomere sleeve with a proximal external sleeve and a distal one way valve * **Articulating joint** * **ankle** * **non articulating**= solid ankle/cushioned heel * **articulating**= uniaxial or multi-axial * **Terminal device** * foot or special device. foot and ankle considered together * **Non energy storing** * *_SACH_*= plantarflexion is stimulated by compression of heel * *_single axis_* foot- passive DF- increase stability in stance phase * *_multiaxis foot_*-adds inversion/everion * **Energy storing** * feet contain deforming components( heel) when compressed rollover, want to return to normal position - provide some eneregy at toe off * **Specialised** * carbon fibre running

Question 30

what is this?

Answer 30

* **Transfemoral prosthesis** 1. _socket- shape important_ * **Convential socket**- plug fit with no anatomical features * **H or Q socket** * ischial tuberosity bearing * flat seat at posteromedial rim * H more pear, Q more rectangular * **Ischial rami containtment** * aims to lock to pelvis medially via the inf pubic ramus and post by containing the ischial tuberosity and transfemoral stump laterally via the greater trochanter 2. _Suspension_ * **rigid plevic band** * **double swived pelvic band** * **roehampton soft suspension** * allows all planes of hip movement * **total elastic suspension belt** * **suction socket** * **elastomeric sleeve suspension** 3. **_articulating joint_** * knee joint- provides stance and swing * stance controlled by * alignment alone * lock * WB control * swing controlled by * external front pick up * internal calf spring mechanism * pneumatic swing phase control * hydraulic swing phase control * microprocessor control * hybrids of microprocessor and hydraulic 4. **_Terminal device- foot and ankle_** * non energy storing * energy storing * speciliased

Question 31

What prosthesis exist for knee and ankle disarticulations?

Answer 31

* 2 types of socket available 1. **differential socket** * outer hard cylindrical socket and an inner liner * liner made from pop of stump and rectified to increase pressure ( grip) over isthmus of the stump 2. **Windowed socket** * a removable window is cut out of the narrowest part of the socket iin order to allow the bulb of the stump to pass thru & the socket to be closed thus maintain suspension

Question 32

What is this?

Answer 32

* **a hip disarticulation prosthesis** * socket and suspension * **ipislateral ischial tuberosity i**s available for WB & **ipsilateral iliac crest for suspension** * although socket is usually suspended over both iliac crests * **Articulating joint** * hip and knee joint- knee similar to transfemoral * hip either * **conventional** * joint lies directly under the socket but causes extra bulk under the socket and asymmetry when sitting * **Four bar** * sited anteriorly on the socket and folds away anteriorly for sitting- avoids aymmetry * connecing tube at hip /knee joints posteriorly to ensure the prosthesis troachanteric knee ankle line is correct for stance stability * **terminal device**- ankle and foot similar to others * energy stroing, non energy storing, specialised

Question 33

What is the socket of a transpelvic prosthesis?

Answer 33

* socket and suspension * usually contralateral ischial tuberosity for weight bearing * **suspension** is from the **contralateral iliac crest** and ispislateral lower ribs * **articulating joint** - hip and knee similar to hip disarticulation * terminal device- foot and ankle- similar to previous